biology Article Human Fatalities Caused by Hornet, Wasp and Bee Stings in Spain: Epidemiology at State and Sub-State Level from 1999 to 2018 Xesús Feás Academy of Veterinary Sciences of Galicia, Edificio EGAP, Rúa Madrid, No. 2-4, 15707 Santiago de Compostela (A Coruña), Spain; [email protected] Simple Summary: Although not frequent, hornet, wasp, and bee stings may be life-threatening. Over the 20-year period studied, a total of 78 fatalities were recorded in Spain, the annual mortality rates ranging from 0.02 to 0.19 per million inhabitants. The fatal events mainly affected men over 65 years of age, and took place in summertime, at “unspecified places”. At regional level, the deaths tended to concentrate in three communities: Galicia, Andalucía, and Castilla y León. Surprisingly, Galicia showed high mortality rates in hornet stings. The implication of the invasive species Vespa velutina, also known as the Asian hornet, is examined. In light of the findings, there is evidence to consider the health-related importance and consequences of Vespa velutina. Abstract: Epidemiology of fatalities in Spain due to hornet, wasp, and bee stings (Cause Code of Death: X23) is described. Over a 20-year period (1999–2018), a total of 78 fatalities were recorded, mostly occurring in males (85.9%), of 65 years and older (52.6%), at “unspecified places” (67.9%), and in the months of July and August (50%). The X23 mortality rates (X23MR) expressed in terms of annual rates and per million inhabitants, varied from 0.02 to 0.19 (mean value ± standard devia- tion = 0.09 ± 0.05), placing Spain at low levels in comparison with other countries. A more detailed and specific breakdown of the distribution of the yearly deaths at the sub-state level and across Citation: Feás, X. Human Fatalities communities reveals some striking features. They were more concentrated in the communities of Caused by Hornet, Wasp and Bee Galicia (35.8%), Andalucía (21.7%), and Castilla y León (12.8%). X23MR were estimated in Galicia at Stings in Spain: Epidemiology at 1.82, 1.10, and 2.22 in 2014, 2016, and 2018, respectively; and in Asturias at 1.88 and 0.97, in 2014 and State and Sub-State Level from 1999 2017, respectively. The role of the invasive species Vespa velutina (VV) is examined. Due to its habits, to 2018. Biology 2021, 10, 73. https:// abundance, and broader distribution, the risk that VV represents to human health is unmatched by doi.org/10.3390/biology10020073 other Hymenoptera native species. Received: 21 December 2020 Keywords: epidemiology; X23; fatalities; venomous animals; Spain; stings; hornets; wasps; bees; Accepted: 19 January 2021 Vespa velutina Published: 20 January 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in 1. Introduction published maps and institutional affil- iations. Insects are important and dominant creatures in nature because of their diversity, ecological role, and influence on natural resources. In fact, insects originate the biological foundation for all terrestrial ecosystems, and every living creature relies, in one way or another, on insects for equilibrium [1]. Certainly the role of insects in human evolutionary history and well-being is indisputable [2]. Copyright: © 2021 by the author. Licensee MDPI, Basel, Switzerland. Social bees and wasps are recognized as important for early hominids. The practice of This article is an open access article harvesting wild bees for honey and wax, as well as hunting wasp colonies for brood and distributed under the terms and nests, survives in our day, although man has now become a beekeeper and an incipient conditions of the Creative Commons wasp breeder. Beehive harvested products (honey, pollen, propolis, bee bread, wax, royal Attribution (CC BY) license (https:// jelly, and venom) have been useful since ancient times, not only as food but also as treatment creativecommons.org/licenses/by/ for medical conditions [3–13]. Wasps too are appreciated as nutritious food and their nests 4.0/). are used therapeutically in traditional medicine [14]. Bees and wasps provide an important Biology 2021, 10, 73. https://doi.org/10.3390/biology10020073 https://www.mdpi.com/journal/biology Biology 2021, 10, 73 2 of 13 service to ecosystems, contributing to the improvement of biodiversity while helping to maintain ecological balance. Moreover, their medical-veterinary importance should also be outlined. Among invertebrate groups, the Hymenoptera represent the only species possessing inoculator’s venom, produced by the venom gland. In the Aculeates, the defining feature is that the egg-laying ovipositor is modified to form a sting [15]. The major insect group causing reaction are those of the genera Apis (honeybees) and Bombus (bumblebees) in the family Apidae; Vespula (yellowjackets), Dolichovespula and Vespa (hornets), and Polistes (paper wasps) of the family Vespidae; and different stinging ants of the superfamily Formicoidea, such as Solenopsis (fire ants) and Pogonomyrmex (harvester ants) [16]. A&E physicians encounter large numbers of hymenopteran sting cases each year. In fact, during their lifetime, 94.5% of people are stung by wasps, honeybees, hornets, or bumble-bees, resulting in an unpleasant experience [17]. Insects are not prone to attack and sting humans; however, social Hymenoptera such as hornets, wasps, and bees: (i) have a massive defensive response to any threat to the colony and (ii) the evolution of the venom system in social Apidae and Vespidae appears to have further evolved to cause pain and augment the immune response in humans and other vertebrate predators [18]. There are five types of reactions to Hymenoptera stings including normal local reac- tions (NLR), large local reactions (LLR), systemic anaphylactic reactions (SAR), systemic toxic reactions (STR), and unusual reactions (UR) [19]. Most stings by Hymenoptera species only lead to a NLR: redness, swelling, itching, and pain. Yet, in a minority of cases (0.02% to 4%) a SAR, sometimes life-threatening, may occur [20]. The prevalence of SAR in epi- demiological studies in Europe to hymenoptera stings ranged between 0.3 and 7.5% in adults and 0.15–3.4% in children [21]. Despite the common event of hymenopteran stings, about 100 million cases are detected each year around the world, fatalities due their stings are statistically rare [17]. Under the current International Classification of Diseases and Related Health Problems 10th Revision (ICD-11), Chapter XX allows the classification of environmental events and circumstances as the cause of injury, poisoning, and other adverse effects. Fatalities due to hornet, wasp, and bee stings (including yellow jackets) are coded as single category, the X23 [22]. The reviewed incidence of insect-sting mortality around the world is statistically low, but not negligible, ranging from 0.03 to 0.48 fatalities per million inhabitants per year [23]. In Spain, the data is scarce. The Spanish Society for Allergology and Clinical Immunology indicates the mortality rate at 0.08 per million inhabitants per year, which means that around 3 or 4 people could die each year from this cause in the event that after sting they did not receive immediate medical attention [24]. Similar values are cited by other authors, with 3 deaths per year (0.08 per million inhabitants and year between 1983 and 1993) [25]. It was highlighted that fatalities due to stinging insects are poorly registered and documented. Furthermore, post-mortem studies suggest that fatal hymenoptera allergy may be underestimated [26,27]. Due to its complex orography and geographic situation, there are marked biogeo- graphical differences in terms of species, populations, and ecosystems throughout Spain. Spain is the most climatically diverse country in Europe, with 13 different Köppen climates. With four biogeographical regions (Mediterranean, Atlantic, Alpine, Macaronesian) several habitats are present to which a variety of hymenopteran communities is associated. In the Iberian Peninsula, just over 9000 species have been cited, which represents 6.13% of the world’s fauna. In fact, Spain possesses one of the richest faunas of hymenopterans in the world [28]. An account of bee species and subspecies recorded in Spain list around 1105 [29]. Current statistics regarding the numbers of apiarists active in Spain show in 2018 a total of 2,868,337 hives registered, which means an average of 5.7 beehives/km2 and 6.1 beehives per 100 inhabitants. The Vespidae family has four subfamilies on the Iberian Peninsula and a total of 162 species are registered so far: 133 Eumeninae, 11 Masarinae, seven Polistinae, and 11 Vespinae [30]. Biology 2021, 10, 73 3 of 13 In the last ten years, three not-native species in the genus Vespa Linnaeus, 1758 have been detected in Spain: (i) the yellow-legged Asian hornet (Vespa velutina Lepeletier 1836), found in 2010 in the community of Navarra [31]; (ii) the black shield hornet (Vespa bicolor Fabricius, 1787) found in 2013 in Málaga (community of Andalucía) [32] and the Oriental hornet (Vespa orientalis Linnaeus 1771) found in Valencia (community of Valencia) in 2012 [33]. The three species have been able to fund stable populations in the entrance areas; however, they differ in their propagation capacity, highlighting the invasive nature alien species (IAS), the Vespa velutina. Accidents due to insect stings, mainly hornet, have been reported in local and national newspapers and other media such as TV, suggesting that the number of people affected might be increasing. In this context of certain